A helmet chin cover as described above is described in, e.g., Japanese Utility Model Publication No. 5-16180. The chin cover described in this reference is comprised of a plate-like attached member serving as an elastic shape retaining member, and a flexible cover member attached to this attached member. When the chin cover is attached to a full-face-type helmet, the upper half of the attached member is interposed between the lower rib member of an outer shell and the impact-on-the-chin-and-cheek absorbing liner, and the lower half thereof is arranged substantially along the lower end face of the impact-on-the-chin-and-cheek absorbing liner. Hence, the flexible cover member is arranged to cover the chin of the helmet wearer from its lower front to a portion below it.
In this state, when the helmet wearer drives the motorcycle, the wind generated by driving which abuts against the chest of the helmet wearer and directed to his chin is blocked by the flexible cover member. Thus, the wind generated by driving is prevented from being dragged between the lower end of the chin cover portion of the helmet and the chin of the helmet wearer to produce a whistling sound.
When this chin cover is attached to a full-face-type helmet, ventilation near the chin of the helmet wearer is not performed well.